1. Field of the Invention
This invention relates generally to an apparatus and method for electronically recording and playing back video images and, more particularly, to an apparatus and method for encoding and recording electronic image information signals in a manner whereby vertical chrominance resolution may be substantially increased upon playback of the coded video signals.
2. Description of the Prior Art
Electronic imaging cameras for recording still images are now well known in the art. Such cameras can record a plurality of still images on a single magnetic disk or tape in either analog or digital format for subsequent playback on any well-known cathode ray tube viewing device or for subsequent recording a hard copy by any one of a variety of copiers such as photographic, thermal, ink jet, etc. Recently, the Japanese have standardized the magnetic disk in which the still images are recorded to a 47 mm floppy disk. In the 47 mm video floppy disk format, each frame of the image is stored as two interlaced fields of odd and even field lines. Luminance information (Y) is stored for every line while each of two chrominance components (R-Y) and (B-Y), i.e., red minus luminance and blue minus luminance, is stored in every other line of every field as shown in Table No. 1 below.
TABLE NO. 1 ______________________________________ Stored Information Frame Line No. Field 1 Field 2 ______________________________________ 1 Y.sub.1, R.sub.1 - Y.sub.1 2 Y.sub.2, R.sub.2 - Y.sub.2 3 Y.sub.3, B.sub.3 - Y.sub.3 4 Y.sub.4, B.sub.4 - Y.sub.4 5 Y.sub.5, R.sub.5 - Y.sub.5 6 Y.sub.6, R.sub.6 - Y.sub.6 ______________________________________
As is readily apparent, each chrominance component (R-Y) and (B-Y) is sampled on two adjacent lines of the full frame image and then not sampled for the next two lines and so on. That offset sampling pattern provides lower vertical chrominance resolution than if each color component were sampled on every other line. The desired every other line color sampling is shown below in Table No. 2.
TABLE NO. 2 ______________________________________ Frame Line No. Sample ______________________________________ 1 R.sub.1 - Y.sub.1 2 B.sub.2 - Y.sub.2 3 R.sub.3 - Y.sub.3 4 B.sub.4 - Y.sub.4 5 R.sub.5 - Y.sub.5 6 B.sub.6 - Y.sub.6 ______________________________________
For a standard interlaced system, the sampling pattern of Table No. 2 would cause each field to contain samples of only one chrominance component so that the odd numbered frame lines (odd field) would contain only R-Y information and the even numbered frame lines (even field) would contain only B-Y information which would be incompatible with the 47 mm video floppy standard.
Therefore, it is a primary object of this invention to provide an apparatus and method in which video image data may be sampled in the manner of Table No. 2 to provide increased vertical chrominance resolution and thereafter coded in a manner that is compatible for recording on the standard 47 mm floppy disk.
It is a further object of this invention to provide an apparatus and method for playing back information recorded in the manner of this invention to enable the reconstruction of images having improved vertical chrominance resolution.
Other objects of the invention will be, in part, obvious and will, in part, appear hereinafter. The invention accordingly comprises a mechanism and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.